1. Field of the Invention
The present invention relates to power line surge suppressors and, more specifically, to surge suppressors which are responsive to a wide input voltage range, e.g., in a range of less than 100 volts to higher than 250 volts.
2. Information Disclosure Statement
Electric and electronic loads receiving power from an external grid is sometimes subjected to high voltage surges. Such surges may arise from inductive loads, lightning strikes or other phenomenon, and may cause damage to or even destroy electric and electronic equipment and devices.
The highest potential transient spike voltages are short in duration, typically tens of microseconds. These high potential strikes may have voltages in the ranges of many thousands of volts, at currents of many thousands of amperes. Such high voltages tend to overstress electronic equipment, components, motors, etc. creating unwanted and hazardous conditions. The high potentials and high current flow cause such drastic stress that permanent damage or destruction results.
In response to these problems, power main frequency isolation transformers in DC power supplies were utilized to obtain energy from the AC power main to isolate power main voltage from the loads for surge protection. However, these devices were costly, large and heavy. In the alternative, to reduce costs, weight and size, switched-mode voltage regulators have been utilized, but these are not fully reliable and may themselves be damaged by high potential surges. Line surge suppressors have also been utilized but have been unreliable when subjected to lightning storm strikes.
U.S. Pat. No. 6,226,162 describes a surge suppression network for single phase and multiphase AC systems which has a voltage clamping device connected in series with a gated crowbar device across the supply voltage in parallel with the load to be protected. A trigger circuit gates the crowbar device on in response to a specified rate of change of the supply voltage indicative of a surge. For higher levels of surge current shunting, pluralities of clamping devices and crowbar devices can be connected in parallel with a single trigger circuit simultaneously turning on all of the crowbar devices for each phase. For crowbar devices such as TRIACs with different response characteristics to positive and negative surges and for unipolar devices such as SCRs, positive and negative subnetworks are connected in anti-parallel across the load.
U.S. Pat. No. 5,610,793 describes a three-stage surge protection circuit. The surge protection circuit includes input terminals for connection to an electrical power supply system and output terminals for connection to equipment to be protected. The three stages comprise: a surge dissipation stage coupled to the input terminals for storing and dissipating transient surge energy across the input terminals; a current limiting stage comprising a pair of inductors, each of which is coupled in series to a respective conductor from said input terminals, for limiting current surges; and a voltage clamping stage comprising an avalanche diode for accurately clamping the voltage to be supplied to the protected electrical equipment to a predetermined level. The surge protection circuit of the present invention can also be provided in a configuration for protecting electrical equipment powered by a three conductor and/or three-phase power system.
U.S. Pat. No. 4,870,534 to the same inventor herein describes a surge suppressor for repeatedly protecting a load against surges occurring on AC power mains from lightning surges or the like. It comprises a first series circuit having a first inductance and a first alternating voltage limiter, including at least a first capacitance and a bidirectionally conductive rectifier circuit, coupled between first and second input terminals. The first inductance conducts substantially all of the current supplied from the A-C power mains. A second series circuit comprising a second inductance and second alternating voltage limiter, including at least a second capacitance and a second bidirectionally conductive rectifier circuit, is coupled across the first alternating voltage limiter and is coupled to first and second output terminals. The first series circuit is arranged for limiting surge currents and voltage excursions passed to the second series circuit to first levels while the second series circuit is arranged for further limiting surge currents and voltage excursions passed to the output terminals to second levels less than first levels.
U.S. Pat. No. 4,870,528 to the same inventor herein describes a surge suppressor which comprises a first series circuit having a first inductance and a first alternating voltage limiter, including at least a first capacitance and a bidirectionally conductive rectifying circuit for charging the first capacitance, coupled between first and second input terminals for limiting surge currents and voltage excursions coupled to first and second load output terminals. The first alternating voltage limiter further comprises a sensing circuit for sensing at least one of the charging current supplied to and the voltage developed across the first capacitance. An auxiliary energy storage circuit and a normally open switching device responsive to the sensing circuit are provided for coupling the auxiliary energy storage circuit across the first capacitance during high energy surge conditions.
Notwithstanding the prior art, the present invention is neither taught nor rendered obvious thereby.
The present invention is directed to a wide input voltage range surge suppressor device. It includes a series circuit means, with a plurality of components, for installation between an AC power input and a downstream load. These components include a nonlinear low pass L-C filter having an inductor and a diode bridge, wherein the diode bridge includes at least one large value capacitor, said filter adapted for attachment to an AC power input. There are two electrolytic capacitors of the nonlinear low pass L-C filter diode bridge in preferred embodiments. These electrolytic capacitor(s) have a rating within the range of about 50 microfarads to about 400 microfarads. The low pass L-C filter diode bridge rectifier diodes are generally rated in the range of about 3 amps, 400 volts to about 6 amps, 800 volts.
There is a two section high pass filter connected to the electrolytic capacitor. This high pass filter has at least two capacitors, preferably diversely rated, and at least three resistors, preferably diversely rated. The two section high pass filter includes at least one capacitor having a rating within the range of about 0.05 microfarads to about 0.5 microfarads, and at least a second capacitor having a rating within the range of about 0.1 microfarads to about 1.0 microfarads. Preferably, the two section high pass filter includes a resistor having a rating within the range of about 100 ohms to about 400 ohms, and at least a second resistor having a rating within the range of about 20 ohms to about 200 ohms, and at least a third resistor having a rating within the range of about 10 ohms to about 200 ohms.
An optional, but preferred voltage offset diode is connected to the two section high pass filter and at least one electronic switch is connected to the voltage offset diode, with at least one capacitor connected to the electronic switch. The electronic switch is preferably a silicon controlled rectifier (SCR) switch
In preferred embodiments of the present invention wide input voltage range surge suppressor there is at least one capacitor connected to the electronic switch and it is at least one electrolytic capacitor of the nonlinear low pass L-C filter diode bridge.
In addition to the foregoing, the present invention wide input voltage range surge suppressor electronic switch includes at least one series resistor for current drive balance assurance.
In some embodiments of the present invention, the capacitor(s) connected to the electronic switch is separate from the one electrolytic capacitor(s) of the nonlinear low pass L-C filter diode bridge and is contained within a separate bridge.